Schizophrenia- Modification 1: Antipsychotic Drugs

  • Created by: curt703
  • Created on: 07-12-18 09:12

Dopamine Hypothesis

  • The most common kinds of drugs used to treat schizophrenia are antipsychotics. These drugs work by altering the effect of dopamine in the brain.

  • Dopamine is a neurotransmitter found in the brain. It has been proposed that schizophrenia may be caused by excess levels of dopamine. It was first noticed in the 1950’s that the drug L-dopa (used for Parkinson’s disease) which increases dopamine levels can produce many of the symptoms of schizophrenia.

  • Research has provided more evidence that there is a link between schizophrenia and dopamine. For example, in experiments, participants can be induced to show positive symptoms of schizophrenia (such as paranoid delusions) by injecting them with drugs that increase the levels of dopamine in the brain.  

  • In the brain, dopamine attaches to dopamine receptors on the dendrites of receiving neurons. This causes the electrochemical impulse to activate in the receiving neuron. However, it has also been discovered that there are actually a number of different types of dopamine receptors known as D1-D5 receptors.

  • Different types of dopamine receptors are found in different parts of the brain. Of interest to psychologists investigating schizophrenia are the D2 receptors that are most commonly found in the limbic system.

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Dopamine Hypothesis

  • The most common kinds of drugs used to treat schizophrenia are antipsychotics. These drugs work by altering the effect of dopamine in the brain.

  • Dopamine is a neurotransmitter found in the brain. It has been proposed that schizophrenia may be caused by excess levels of dopamine. It was first noticed in the 1950’s that the drug L-dopa (used for Parkinson’s disease) which increases dopamine levels can produce many of the symptoms of schizophrenia.

  • Research has provided more evidence that there is a link between schizophrenia and dopamine. For example, in experiments, participants can be induced to show positive symptoms of schizophrenia (such as paranoid delusions) by injecting them with drugs that increase the levels of dopamine in the brain.  

  • This is a system of subcortical structures that are engaged in many functions, particularly emotions, memory and arousal. Too much dopamine activating the D2 receptors in the limbic system could cause over stimulation, and may explain some of the positive symptoms such as delusions and hallucinations.

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Antipsychtotic Medicine

  • In the 1950s, a revolution occured in the treatment of schizophrenia. Until this time, the only available treatments for the illness were electroconvulsive shock therapy (ECT), insulin shock therapy, psychosurgery, or institutionalisation. These therapies were ineffective, and some had terrible side effects.

  • However, the creation of the first antipsychotic drug chlorpromazine revolutionised the treatment of schizophrenia. It improved symptoms enough so that schizophrenics could be discharged from hospital. However, at the time, psychiatrists did not know exactly how the drug worked.

  • Since then, there have been dozens more types of antipsychotic developed. They vary in the mechanism of function and side effects. There is also a great variety in the effectiveness of different drugs between individuals, there is no one cure all drug that works on all schizophrenics. It is also worth noting that none of the drugs here provide a cure for the illness.

  • However, the right dosage and combination of drugs can allow schizophrenics to control their symptoms, and even live relatively normal lives.

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Conventional Antipsychotics

  • The first antipsychotic drug widely used was chlorpromazine. Interestingly, this compound had originally been developed in the 1880s as a synthetic dye. It was then developed as an antihistamine, and the as an anaesthetic booster. In 1952, it was trailed on a single 24-year-old manic patient. The results were so dramatic that the patient was able to be sent home three weeks later.

  • Further clinical trials later the same year found a dramatic reduction of psychotic symptoms in 38 patients. After further trials, the drug was then mass produced.

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Differences between conventional and atypical anti

While both types of antipsychotics perform similar functions and have similar effects, there are some differences between them.

Seeman (2002) “Fast-Off”: This proposes that atypical antipsychotics bind more loosely to the D2 receptor sites than conventional antipsychotics. Meaning that although the blockade has a therapeutic effect, it doesn’t last long enough to also produce the side effects seen in conventional antipsychotics.

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Evaluation (Effectiveness)

There is not a one size fits all drug that can be given to all schizophrenics. Depending upon individual differences and the exact symptoms of the schizophrenic, different drugs produce different effects. Also, the side effects experienced by each patient may be vastly different, and in some cases, the side effects may actually be worse than the illness itself. This means that when investigating the effectiveness of different types of antipsychotics, we need to bear in mind that the findings of these studies only give us an idea of the general trends in terms of effectiveness. Just because a particular drug is shown to be less effective than another, it doesn’t mean that the drug is useless. Some individuals may actually respond better to the drug that, on average, show a lower effectiveness. Getting the right combination and dosage of medication is often a case of trial and error.  

Cole et al (1964)- They looked at the effectiveness of antipsychotic drugs. The findings suggested that psychiatry could treat mental disorder in the same way that physical orders are treated.

Ravanic et al (2009)- They compared the effectiveness of clozapine, chlorpromazine and haloperidol in 325 individuals with schizophrenia. They found that over a period of 5 years, there were significant differences in psychometric scores measuring schizophrenic symptoms, favouring clozapine.

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Ethical Implications

Side Effects            

  • Tardive Dyskinesia- Involves involuntary writhing or tic like movements of the tongue, mouth, face or whole body.

  • Parkinsonism- Tremors and instability

  • Agranulocytosis- A potentially life threatening drop in white blood cells.

Consent: If they are having an acute “episode” of the disorder they cannot fully consent to the drug.

Chemical Straightjacket:

  • Not all psychologists and psychiatrists are convinced that medication is the best way to treat schizophrenia.

    • Szasz (1960)- Amongst others in the antipsychiatry movement argue that medication is being used in the same way as a straightjacket. Antipsychotic medication isn’t being used with the aim of reducing the suffering of the schizophrenic, but rather as a way of making the patient more compliant and to make them conform to society’s view of “normality”.

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Social Implications

  • Before antipsychotic medication became widespread, the treatment options for schizophrenics were limited. Many schizophrenics were hospitalised indefinitely in psychiatric hospitals or “asylums”.

  • Schizophrenia was seen as an incurable, chronic condition, and schizophrenics were simply written off as untreatable. The treatments that were used were cruel, ineffective, and used primarily as a way of controlling and subduing aggressive patients rather than as a way of reducing their suffering.

  • The introduction of the first antipsychotic, chlorpromazine, sparked a revolution in the treatment of schizophrenia. Within weeks of first taking the medication, patients were able to be released from hospital, and back into the community. The impact that antipsychotics had on treating psychosis has been compared to the impact that penicillin had on the treatment of infection.      

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